1. Field of the Invention
This invention generally relates to apparatus for handling roll paper, which is continuously long paper wound in the form of a roll, and particularly a roll paper handling structure which may be advantageously used in various types of recording machines, such as facsimile machines and copiers, which use recording paper in the form of a roll.
2. Description of the Prior Art
Many recording machines, such as facsimiles and copiers, use recording paper in the form of a roll instead of cut sheets. In such recording machines, the recording paper is unwound from the roll and after having recorded desired information, is severed to a desired size. When the remaining amount of roll paper becomes scarce, it must be replaced with a new roll. And, in order to facilitate such a replacement operation, it has been proposed to use an installation box which is structured to receive therein roll paper and which may be pulled out of the machine, However, since the leading portion of the paper unwound from the roll received in the box is normally located in a paper passage, which includes a recording seciton, where a recording element, such as a thermal printhead, is provided, and which is defined, for example, by rollers and guide plates outside of the box. Thus, if the installation box is drawn out with the leading portion of the roll paper located in the paper passage, the paper will be torn undesirably. This is disadvantageous because the torn paper might block the paper passage, thereby necessitating to remove the torn paper and possibly readjustments.
Moreover, the roll paper is normally supported rotatably in the installation box and in order to make a paper feeding operation as smooth as possible as unwound from the roll, it is desired to support the roll paper rotatably as smoothly as possible. However, the roll paper is normally rotated intermittently because it must be cut to sizes after recording. Thus, the roll will be excessively rotated if the roll is supported to be freely rotatable. In order to prevent the roll from rotating excessively during its intermittent rotating operation, it has been proposed to apply so-called back tension to the roll thereby applying a force which tends to resist the roll from rotating in the unwinding direction. However, the prior art structure for applying such back tension was relatively bulky and complicated, and furthermore, in the prior art structure it was not easy to maintain the level of back tension constant.